Resembling nothing so much as Chewbacca's children, two of the world's tiniest monkeys debuted recently at the Frösö Zoo in Ostersund, Sweden.

Shown here shortly after their birth, these pygmy marmosets are exceedingly rare. It's not because they're twins thoughpygmy marmosets are typically born in pairsbut because they're albinos, deficient in pigment.

The world's smallest species of monkey, this tree-dwelling marmoset makes big noise, contributing clicks, whistles, and squeals to the cacophony of their home habitat, the western Amazon rain forest of South America. Adults grow to about 5 inches (13 centimeters) in length and weigh about 6 ounces (170 grams).

Sadly, one of the twins didn't get any bigger than it was in the photo.

"We were so sorry when the twin died," zoo owner Ake Netterstrom told London's Daily Mail. "We put in all available resources to save him, but that did not help.